It lets you share 25%, 50%, 75%, or 100% of your adsense revenue by displaying your member advertisements based on a smart algorithm.

The revenue sharing plugin has 4 kinds of "weight" giving ways, which boost a user's chance of earning. Any one of these can be used on per-forum basis:

1. Repliers get more weight
As you can guess, using this will boost chances of ads display for repliers, 3 times more than the thread starter. This is ideal for the sections where users ask for help and other users offer voluntary help.
2. Topic starters get more weight
Using this the topic starters get 3 times more chances of having their google ads displayed. It can be better used in sections where users are start discussions that can be helpful in getting crowd.
3. Equal Weight
Both the thread starter and repliers get equal chance of having their ads displayed, using this setting.
4. Only topic starters get weight
Simple, as it says! It's either the site admins ads (if sharing is not 100%), or the topic starters ads in this section, where this setting is enabled.